Various methods for opening a fiber bundle, particularly a bundle of crimped fibers for use in a brush part or the like of a cleaning member have been being considered.
For example, PTL 1 describes a method of opening continuous filaments, the method including transporting crimped tow by means of a plurality of rolls; and applying a resistance on at least one side of the tow by slidingly contacting at least one sliding body onto the tow at between rolls, whereby continuous filaments stacked in a thickness direction of the tow are caused to sift in a transporting direction of the tow to open the tow and to spread the continuous filaments in a width direction of the tow.